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Article

Measurement of Branching Fractions of Λ+c→ηΛπ+, ηΣ0π+, Λ(1670)π+, and ηΣ(1385)+

Аушев Т. А., Mizuk R., Pakhlov P., Pakhlova G., Попов В. Е., Углов Т. В.

We report branching fraction measurements of four decay modes of the Λ+c baryon, each of which includes an η meson and a Λ baryon in the final state, and all of which are measured relative to the Λ+cpKpi+ decay mode.
The results are based on a 980 fb−1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e− collider.
Two decays, ηΣ0π+ and Λ(1670)π+, are observed for the first time, while the measurements of the other decay modes, Λ+cηΛπ+ and ηΣ(1385)+, are more precise than those made previously.
We obtain B(Λ+cηΛπ+)/B(Λ+cpKπ+) = 0.293±0.003±0.014, B(Λ+cηΣ0π+)/B(Λ+cpKπ+) = 0.120±0.006±0.006, B(Λ+c→Λ(1670)π+)×B(Λ(1670)→ηΛ)/B(Λ+cpKπ+) = (5.54±0.29±0.73)×10−2, and B(Λ+cηΣ(1385)+)/B(Λ+cpKπ+) = 0.192±0.006±0.016.
The mass and width of the Λ(1670) are also precisely determined to be 1674.3±0.8±4.9 MeV/c2 and 36.1±2.4±4.8 MeV, respectively, where the uncertainties are statistical and systematic, respectively.